It doesn't seem to me that this has/had anything to do with freedom of expression, but that it did have a lot to do with safety. As a once-regular and now sometimes attendee, it has always been my understanding that Folklife doesn't ban buskers, as such, but they do regulate them. Performing in covered walkways is specifically banned under the street performer rules. Anyone who has ever been to Folklife knows that it is very crowded and that having a crowd stopping to watch a performer in a cramped area quickly brings movement to a complete halt.

I don't know where Mr. Miles was, but I can only think of 2 covered walkways at Seattle Center. Both are about 8-10 feet wide; one has a wall on one side and a pond on the other and the other has vendors' booths on both sides during Folklife. There is a 3rd covered area where a flight of steps passes between two buildings, and 1 of the entrances is enclosed. Walking through any of these when they are jammed with people is difficult, even if the crowd keeps moving.

It sounds a lot like the old "freedom of expression doesn't let you yell 'fire' in a theater" issue to me.